Rotary air pump



April 13, 1926. 1,580,237,

A. 'J. ESPITALLIER ROTARY Filed Feb. 26. 1925 AIR PUMP 2 Sheets-Shoot 1 29 i W I WFW April 13 1926.

v 1,580,237 A. J. ESPITALLIER' ROTARY Am Pukr Filed Feb. 26, 1 5 2 Sheets-Sheet 2 Patented Apr. 13, 1926.

UNITED, STATES.

ANDREW J. ,ESPITALLIER,

OF AURORA, ILLINOIS, ASSIGNOR T0 HIMSELF AND EARL L.

cunnnm'or AURORA, ILLINOIS.

BOTARY'AIR Pour.-

llpplicationfiled February 2e, 1925. Serial No. 11,644.

To all whom it may concern:

Be it known that 1, ANDREW J. EsrrrAL- LIER, a citizen of theUnited States, residing in Aurora, county of Kane, State of Illinois, have invented a certain new and useful Improvement in Rotary Air Pumps, and declare the following to be a full, clear, and exact description of-the same, such as will enable others skilled in the art to which it pertains to make and usethe same, reference being had to the accompanying drawings, which form a part of this specification.

The present invention has for its object to produce a simple, novel, efficient and inexpensive air pump in which the mechanism as a whole may bedriven by belt; or otherwise, about a stationary supporting shaft; the pump to be particularly adapted to be driven from mobile for pumping air into the tires, but being of course useful for other purposes.

The various features of novelty whereby my invention is characterized will hereinafter be pointed out with particularity in the claims; but for a full understanding of my invention and of its objects and advantages, reference may be had to the following detailed description-taken in con nection with the accompanying drawings, wherein:

Figure 1 is aside elevation of pump arranged in accordance with my invention; Fig. 2 is a vertical central section taken. at right angles to the axis of rotation; Fig. 3 is a central section taken approximately at the axis of rotation of the pump Fig. 4 is a perspective view of one of the pump cylinders; Fig. 5 is a perspective view of one of the pistons; and Fig. 6 is a section at ri ht angles to the axis of rotation through a fragment of the housing or cas- 1ng at the rim or periphery.

Referring to the drawings, 1 represents a shaft that may be supported in any suitable way sofasto be held stationary. In the arrangement shown, the shaft is screwthreadecl at one end and extends through a bracket 2, there being nuts 3 and 4 on the shaft on opposite sides of the bracket.

Surrounding the shaft is a'casing or housing, preferably inthe form of a short cylinder. This casing or housing may of the fan belt of an autocourse take various forms, although it is conveniently made of two similar members pressed out of sheet metal, each member comprising a discslike center 5 having a pro jecting hub or sleeve .6 at the center, a plur ality'of radial arms 7 extending from the disc to asuitable annular flange or rim 8. In assembling the two parts of the casing or housing I prefer toplace between the meeting edges of the two flanges or rims a ring 9 having a cross section in the shape of an invertedT having a short'stem.

The stem of the section fits between the meeting edges of the parts of the casing or housing while the cross member underlies the portions of the two flanges adjacent to. saidoedges. The parts of the casing or housing are conveniently fastened together by means .of bolts through the same just within the periphery. One of the hubs 6; may abut against the nut 4, and there may be a large headed set screw 11 at the opposite end of the shaftfor engaging with the other hub.

On the shaft, within the casing or housing,-'is an eccentric 12. The eccentric is preferably made ,wide in the direction of the length of the shaft so as to provide a large peripheral surface. As best shown in Figs. 2 and 3, there is a radial passage 13 extending inwardly from the periphery of the eccentric, this passage being controlled by an outwardly seating check valve 14. The shaft is provided with an axial'passage 15 leading out through onev end of the shaft from'the inner end ,ofthe passage 13; the passages 13 and 15 constituting the discharge outlet for the pump. If desired, an air hose nipple 16 may bescrewed into the outer end of the passage 15 for receiving a suitable hoseconnectiolr- I Surrounding the eccentric are a plurality of cylinders, three being shown and each being indicated by the reference number 17. Each cylinder is open at its outer end and closed at the end adjacent to the eccentric by a wall 18 curved to fit upon the eccentric Each-of these walls is approximately 120 degrees in angular length, measured in a plane at right angles to the long axis of the shaft, and has a width somewhat greater than the external diameterv of the cylinder, so as to provide projecting flanges at the op- 10 passing transversely posite sides of the cylinders. Each cylinder must be permitted to oscillate to some extent and therefore, in order that the effective angular length of the wall 18 may be made as great as possible, I cut a wide notch 19 in one end of the wall and provide the opposite end with a projection 20; the projection on each cylinder projecting into the notch in the wall of the adjacent cylinder Each wall 18 has at about the middle a small port 21 extending entirely through the same; this port lying in a plane at right angles to the axis of rotation and containing the outer end of the passage 13 in the eccentric. Therefore whenever one of the ports 21 registers with the outer end of the passage 13, communication is established between the interior of the corresponding cylinder and the outlet passage from the pump. When the cylinders are revolved about the eccentric, each of the ports 21 can remain in complete or partial registration with the passage 13 for only a very short time, and I have therefore placed in the bearing face of each wall 18 a groove 22 extending in opposite directions from the port 21, lengthwise of the wall; the groove terminating short of the ends of the walls. Therefore each cylinder will remain in communication with the outlet passage as long as a portion of the groove in its bearing face registers with such passage.

The cylinders may conveniently be held in proper relation to the eccentric by means of two rings 23 lying on opposite sides of the cylinders and each overlying the laterally projecting parts or flanges of the three walls 18. In other words, the lateral projections of the walls are fitted into the rings 23. The rings 23 preferably engage with the sides of the casing or housing so as to hold the cylinders against displacement lengthwise of the shaft; these rings alsotaking the wear between the cylinders and the casing or housing when the cylinders are reciprocated as will now be explained.

In each cylinder is a short piston 24 that is preferably provided with a leather cup packing 25. Each piston is hung from its outer end so as to be capable of swinging about an axis parallel with the axis of rotation. This may conveniently be accomplished by utilizing the bolts 10, which fasten the parts of the casing together, as wrist pins that extend through the outer ends of the pistons.

In operation, when the casing or housing is rotated upon the shaft, the eccentric pushes one cylinder after the other away from the axis of rotation, thus causing the air contained in each cylinder to be compressed and forced out through the outlet passage of the pump; the passage 13 opening out through what may be termed the high portion of the eccentric. After a cylinder has been forced outwardly, it would probably stay there unless positively returned to make a suction stroke. The two rings 23 tie all of the cylinders together so that their movements must bear definite relations to each other. Therefore when the eccentric is moving into a position to force one cylinder outwardly, another cylinder is being drawn inwardly by the rings which therefore serve positively to move the cylin-, ders through their suction strokes. In other words, the rings 23 are eccentric straps which, instead of bearing directly on the eccentric, engage with flanges on the cylinders to hold the cylinders against the cocentric. An inlet to the cylinders is pro vided by cutting a helical groove 27 on the periphery of the eccentric 12 leading to a small recess on same, located diametrically opposite to the outlet post 14.

If desired, the periphery of the casing, that is the cylindrical rim, may be provided with transverse corrugations, as indicated at 26in Fig. 6, in order to increase the tractive effect of the belt or other driving member.

While I have illustrated and described with particularity only a single preferred form of my invention, I do not desire to be limited to the exact structural details thus illustrated and described; but intend to cover all forms and arrangements which come within the definitions of my invention constituting the appended claims.

I claim:

1. A pump comprising a shaft and a surrounding casing rotatable relatively to each other, an eccentric on the shaft within the casing, a plurality of radial pistons hung in the casing for oscillation about axes parallel with the axis of rotation, a cylinder surrounding each piston and fitted against the periphery of said eccentric, each cylinder having a lateral projection, and a ring surrounding said shaft and overlying the projections on all of the cylinders to hold the cylinders to the eccentric.

2. A pump comprising a shaft and a surrounding casing rotatable relatively to each other, an eccentric on the shaft within the casing, radial pistons distributed about the eccentric and held against radial movements relatively to the casing, cylinders surrounding the pistons, an eccentric strap, and each cylinder having a portion underlying the strap and held by the same against the eccentric.

3. A pump comprising a shaft and a surrouding casing rotatable relatively to each other, an eccentric on the shaft within the casing, radial pistons distributed about the eccentric and held against radial movements relatively to the casing, cylinders surrounding the pistons and having curved heads shaped to fit the periphery of the eccentric, said heads projecting laterally to form Y shaped to fit the periphery of the eccentric,

said heads projecting laterally to form flanges displaced from each other lengthwise of the shaft, eccentric straps fitted over said flanges, each head having a port therethrough terminating in a groove extending in the direction of rotation in the bearing face of the head, the shaft and the eccentric having an outlet passage extending lengthwise of the shaft and then outwardly through the eccentric in the plane of the said grooves, and a check valve in said passage. 7 p

5. A pump comprisinga stationary shaft, a cylindrical casing coaxial with the shaft and rotatable thereon, said casing being divided into two parts on a plane transverse to the shaft, an eccentric on the shaft within the casing, a plurality of radial pistons distributed about said eccentric, wrist pins extending through the.outer ends of the pistons and the two parts of the casing parallel with said shaft to hold the casing togetherand support the pistons for swinging movements, cylinders surrounding the pistons and bearing on the eccentric,

cylinders surroundan eccentric strap, and each cylinder having a part fitting between said strap and the eccentric.

'6. A pump comprising a stationary shaft, a cylindrical casing coaxial with the shaft and rota-table thereon, said casing being divided into two parts on a plane transverse to the shaft, an eccentric on the shaft within the casing, a plurality of radial pistons distributed about said eccentric, wrist pins extending through the outer ends of the pistons and the two parts of the casing parallel with said shaft to hold the I casing together and support the pistons for swinging movements, cylinders surrounding the pistons and bearing on the eccentric, each cylinder having lateral projections at opposite rounding said projections to hold the cylinders to the eccentric, the parts being so proportioned that the straps engage with the sides of the casing and formfwearing shoes for the cylinders. I v

7. A pump casing comprising a short cylinder made of sheet metal and divided into two similar cup-shaped parts on a v plane transverse to the longitudinal axis of the cylinder, a ring lying within the cylinder and engagingwith the marginal por-. tions adjacent to the meeting edges, a rib on said ring fitting between said meeting edges, and bolts passing through the ends of the casing to hold it together.

In testimony whereof, I sign this speci-' fication.

sides, and two eccentric straps sur ANDREW J. ESPITALLIER. 

